diff --git a/icu4c/source/test/iotest/iotest.cpp b/icu4c/source/test/iotest/iotest.cpp
index 4cdf6833379..6ced2811cb2 100644
--- a/icu4c/source/test/iotest/iotest.cpp
+++ b/icu4c/source/test/iotest/iotest.cpp
@@ -27,7 +27,7 @@
 
 #if U_IOSTREAM_SOURCE >= 199711
 #include <iostream>
-#ifdef U_LINUX
+#if defined(U_LINUX) || defined(U_CYGWIN)
 #define USE_SSTREAM 1
 #include <sstream>
 #else